Progressive resistance exercise increases strength but does not improve objective measures of mobility in young people with cerebral palsy

Abstract

Question: Does progressive resistance training (PRT) improve mobility and muscle strength in young people with cerebral palsy (CP)?

Design: Randomised, controlled trial with concealed allocation and blinded outcome assessment.

Setting: Recruitment from a large metropolitan children's hospital and a CP register in Australia.

Participants: Participants had spastic diplegia CP, were aged 14 years to 22 years, had a disability classified as level II or III on the Gross Motor Function Classification System. Exclusion criteria were participation in PRT in the previous six months, single-event multi-level surgery in the previous two years, or contractures more than 20° at the hips and knees. Randomisation of 49 participants allocated 24 to the PRT group and 25 to the control group.

Interventions: The intervention group participated in a twice-weekly, 12-week PRT program performed at community gymnasia. Training was completed alone or in pairs under the supervision of a physiotherapist. Each participant was prescribed four to six individualised exercises, which were targeted to address deficits that had been identified by instrumented gait analysis, supplemented by clinical assessment. Participants completed three sets of 10 to 12 repetitions of each exercise at an intensity of 60% to 80% of one repetition maximum (RM). The control group continued with their usual recreation and physiotherapy provided it did not include PRT.

Outcome measures: The primary outcome was the six-minute walk test at week 13 and at week 24. Secondary outcome measures assessed objective mobility-related function (self-selected walking speed, timed stairs test, Gross Motor Function Measure (GMFM-66) dimensions D and E, Gait Profile Score), participant-rated mobility (Functional Mobility Scale, Functional Assessment Questionnaire) and muscle performance (1-RM) of leg press and reverse leg press).

Results: Forty-eight participants completed the study. After 12 weeks of training, there was no difference between the groups for the six-minute walk (0.1 m, 95% CI -20.6 to 20.9), stairs test (-0.9 s, 95% CI -4.7 to 2.9), GMFM dimension D (-1.3%, 95% CI -4.8 to 2.4) and E (0.9%, 95% CI -3.0 to 4.7), and reverse leg press 1-RM (-0.7 kg, 95% CI -4.3 to 2.8). The intervention group showed significant improvement in the Functional Mobility Scale at 5 m (0.6 units, 95% CI 0.1 to 1.1), the Functional Assessment Questionnaire (0.8 units, 95% CI 0.1 to 1.6) and leg press 1-RM (14.8 kg, 95% CI 4.3 to 25.3), compared with the control group. At week 24, there were no differences between the groups for any outcome. The groups did not significantly differ for the remaining secondary outcomes at either time-point.

Conclusion: Individualised PRT increases strength in young people with CP. The participants thought their mobility had improved, although objectively it had not.